F02. Tachycardia-triggered vagus nerve autostimulation using the AspireSR 106 model in patients with refractory epilepsy: Treatment outcome between de novo implantation and replacement of old models. (May 2018)

• Record Type: Journal Article
• Authors: Zhong, Ning; Chen, Leo; Johnstone, Anne K.; Luong, Dorris
• Is Part Of: Clinical neurophysiology. Volume 129(2018)Supplement 1
• Page Start: e66
• Page End: e67
• Publication Date: 2018-05
• Subjects: Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2018.04.165
• Languages: English
• ISSNs: 1388-2457

Abstract

Abstract : Introduction: Vagus nerve stimulation (VNS) therapy with open-loop stimulation has been shown to effectively reduce the frequency or severity of seizures. Manual application of the magnet to trigger extrastimulation at the time of the perceived seizure onset may not be feasible in some patients. The automatic stimulation mode (AutoStim, closed-loop) feature of AspireSR 106 model, triggered by ictal tachycardia (IT), aims to terminate a seizure or to reduce severity. We presented a novel series to further refine the benefit of AutoStim. Methods: We retrospectively analyzed seizure frequency, severity, and clinical outcome in 24 adult patients with AspireSR 106 implanted between 8/2015 and 7/2017; 13 were replacements of old models, and 11 de novo implantation. Results: Pre-implantation: all patients failed more than 2 antiepileptics, with more than 3 seizures each month. No severe post-implantation adverse events were reported. 13 patients (5 M/8F, median age 32, mean followup 13.6 months) underwent replacement of old models. Malfunctional VNS were found in 6 patients, only two patients reported less frequent seizures. Near end of service or low battery was reported in 7 patients, none reported changes in seizure frequency, but one patient noted reduced severity. 11 patients (4 M/7F, median age 40, mean followup 8.7 months) were de novo implantation. Prior to implantation, 9 patients were monitored in EMU, of whom 4 were found with IT (identified as 50% HR increases from pre-ictal baseline). IT detected by AspireSR 106 at seizure onset was confirmed by EEG monitoring in one patient post-implantation. While followup, time-stamp data were retrieved in 3 patients and showed 60–70% match rate between IT detection and the reported seizures. Average seizure reduction was 37 ± 11% in all 11 patients. Within this group, 8 patients (4 with IT) reported good seizure control, of whom 5 patients had over 50% reduction in frequency and notable decreases of severity, 3 patients reported dramatic decreases of severity with 13.9% reduction in frequency. One patient elected to turn off AutoStim for 2 months, increased aura frequency was noted during the AutoStim OFF period. The frequency was dramatically decreased after AutoStim was resumed. One patient elected not to turn on the AutoStim feature for 6 months after the implantation. The seizure frequency was reduced ∼40% during the open loop stimulation period. It produced a further 70% reduction in frequency and significantly decreased severity with AutoStim turned on. Conclusion: Our data have suggested that, with pre-implantation monitoring and identification of IT, the combined open- and closed-loop stimulation delivered by AspireSR 106 may exhibit greater efficacy in seizure control. The AutoStim has an acceptable specificity of triggering VNS at seizure onset. The discrepancy between the replacement and de novo group raises the question about best utilization, which should prompt larger studies to confirm the clinical efficacy of AutoStim in different groups.